The thymidine dideoxynucleoside analog, alovudine, inhibits the mitochondrial DNA polymerase γ, impairs oxidative phosphorylation and promotes monocytic differentiation in acute myeloid leukemia

Abstract

Mitochondrial DNA encodes 13 proteins that comprise components of the respiratory chain that maintain oxidative phosphorylation. The replication of mitochondrial DNA is performed by the sole mitochondrial DNA polymerase γ. As acute myeloid leukemia (AML) cells and stem cells have an increased reliance on oxidative phosphorylation, we sought to evaluate polymerase γ inhibitors in AML. The thymidine dideoxynucleoside analog, alovudine, is an inhibitor of polymerase γ. In AML cells, alovudine depleted mitochondrial DNA, reduced mitochondrial encoded proteins, decreased basal oxygen consumption, and decreased cell proliferation and viability. To evaluate the effects of polymerase γ inhibition with alovudine in vivo , mice were xenografted with OCI-AML2 cells and then treated with alovudine. Systemic administration of alovudine reduced leukemic growth without evidence of toxicity and decreased levels of mitochondrial DNA in the leukemic cells. We also showed that alovudine increased the monocytic differentiation of AML cells. Genetic knockdown and other chemical inhibitors of polymerase γ also promoted AML differentiation, but the effects on AML differentiation were independent of reductions in oxidative phosphorylation or respiratory chain proteins. Thus, we have identified a novel mechanism by which mitochondria regulate AML fate and differentiation independent of oxidative phosphorylation. Moreover, we highlight polymerase γ inhibitors, such as alovudine, as novel therapeutic agents for AML.

A genome-wide CRISPR/Cas9 screen in acute myeloid leukemia cells identifies regulators of TAK-243 sensitivity

“…After the tumors became palpable, mice were randomly divided into 4 groups ( n = 5 per group) and treated with vehicle (10% HPBCD in water) or TAK-243 at doses of 10, 15, and 20 mg/kg s.c. BIW for 3 weeks. Mice were weighed and tumor volumes were measured by caliper measurements every 2–3 days using the following equation: tumor volume in mm 3 = tumor length in mm × width 2 in mm × 0.5236 as previously described ( 59 ). At the end of the experiment, mice were euthanized and tumors excised for weighing.…”

Global Interactome Mapping of Mitochondrial Intermembrane Space Proteases Identifies a Novel Function for HTRA2

“…We and others have previously shown that acute myeloid leukemia (AML) cells possess unique mitochondrial characteristics, with increased reliance on oxidative phosphorylation . Knockdown of HTRA2 also disrupted cristae structure in the AML cell line OCI‐AML2 (Figure B).…”

Characteristics and outcome of patients with acute myeloid leukaemia and t(8;16)(p11;p13): results from an International Collaborative Study*

“…We found a large number of secondary mutations, including mutations in tumour suppressor and myeloid tumour factor genes as well as transcriptional suppressor and chromatin modifier genes. Besides well‐described mutations in AML, we found mutations in POLG , which is responsible for mitochondrial DNA replication 47 as well as mutations in MLH1 , which belongs to the DNA mismatch repair system and plays an important role in maintaining genomic stability 48–52 . Whereas both mutations were described to increase the risk of hereditary and sporadic cancers, 48,50,52,53 their incidence and clinical impact in AML are less well defined.…”